Many different types of wells into the Earth's subsurface exist. For example, a borehole may be drilled to create a well for accessing hydrocarbons. As another example, geothermal wells are used to access the Earth's natural heat. Continuing with the example, wells are used to access water, vent mines, rescue people from mines, and obtain hydrocarbons from a formation. Each type of borehole requires a process for drilling the well.
For example, obtaining downhole fluids (e.g. hydrocarbons) typically require a planning stage, a drilling stage, and a production stage. Each stage may be performed one or more times. In the planning stage, surveys are often performed using acquisition methodologies, such as seismic mapping to generate acoustic images of underground formations. These formations are often analyzed to determine the presence of subterranean assets, such as valuable fluids or minerals, or to determine whether the formations have characteristics suitable for storing fluids. Although the subterranean assets are not limited to hydrocarbons such as oil, throughout this document, the terms “oilfield” and “oilfield operation” may be used interchangeably with the terms “field” and “field operation” to refer to a site where any types of valuable fluids or minerals can be found and the activities required to extract them. The terms may also refer to sites where substances are deposited or stored by injecting them into the surface using boreholes and the operations associated with this process.
During the drilling stage, a borehole is drilled into the earth at a position identified during the survey stage. Specifically, a drilling rig rotates a drill string that has a bit attached. Casing may be added to ensure the structural integrity of the borehole. The trajectory, or path in which the borehole is drilled, may be controlled by a surface controller. Specifically, the surface controller controls the drill string to ensure that the trajectory is optimal for obtaining fluids.
During the completion stage, the drilling equipment is removed and the well is prepared for production. During the production stage, fluids are produced or removed from the subsurface formation. In other words, the fluids may be transferred from the subsurface formation to one or more production facilities (e.g. refineries).